Project Summary: The broad aim is to improve understanding of the child overweight epidemic and begin to identify possible public policies to address the epidemic. The immediate aim is to identify the changes in a child's neighborhood environment that affect their overweight status and measure the impact of each environmental change. The true impact of an environmental factor is difficult to measure because of unobserved differences across families can affect their location choices and their use of an environmental factor. Natural experiments are a way overcoming the bias due to any unobservable cross-family differences. The changes in the immediate environment include the addition or removal of playgrounds, pools, jogging paths, athletic fields, fast food restaurants, supermarkets, and convenience stores. Changes in the immediate environment constitute a natural experiment for the children who live at the same address before and after the change. The method is to create a panel data set based on clinical information on approximately 35,000 children between 1992 and 2007 including their measured heights and weights and addresses and to connect each child to the changes in their immediate environment through a city-wide geographic information database. Impacts will be measure as functions of their network distance and of time for up to six years after an environmental change. A second phase of the project is to survey 2,000 parent-child pairs that live near the environmental changes that had the highest estimated impact on child overweight in the initial data and obtain behavioral information on the before-and-after use of the environmental factors. The estimation strategy is to use fixed effects and difference-in-difference estimators to isolate the impact of environmental changes while obtaining more precise estimates of the social factors that affect child overweight including the family's medical insurance status, race, education, and composition. Relevance: The US child overweight epidemic and its long-term health consequences are well documented. The location of this study, Indianapolis, is among the worst in the nation in terms of the percentage of overweight children. This project will measure the impact of changes in the immediate neighborhood environment on children's diets and exercise and thus begin to identify possible public policies to address the epidemic. [unreadable] [unreadable] [unreadable]